Iron/phosphate conversion surfaces were first discovered in 1869 in England and a Patent was granted under the English Patent Laws. There then followed a series of improvements on the basic process. These improvements allowed for faster conversion rates, better cleaning procedures, and addition of other metal ions such as zinc, manganese, or nickel etc., to achieve an iron-phosphate coating with a bi-metallic element such as zinc-phosphate or manganese phosphate. These bi-metallic phosphate surfaces gave different properties which enhanced the usefulness of the iron-phosphate surface.
There is an extensive amount of literature on phosphatizing, mostly contained in patents issued on phosphating processes. In 1969 METAL FINISHING presented abstracts of 522 patents issued on phosphatizing processes.
Iron/phosphate surfaces and their derivatives became one of the most widely used surfaces for industrial applications in the world. The iron/phosphate conversion surfaces have excellent keying points for retention of paints and are widely used as an undercoat for paints in truck and car bodies, file cabinets, shipping containers, and many other uses as a paint undercoat.
Additionally, the iron-phosphate surface provides excellent corrosion protection to prevent oxidation of steel parts. The iron phosphate surface has a lower co-efficient of friction than steel, and provides dry film lubricity on moving and sliding steel parts. The surface also has excellent retention of oil properties which enhance the lubricating effect of oils.
The application techniques of a phosphating line include baths for removing all soils and oils from the steel surfaces in order for the conversion to occur. It is well known in the art that the preparation of the metal surface, particularly the removal of oils, is required in order for the conversion process to occur. A brief description of a phosphatizing system consists of a hot alkaline bath to remove oils, a rinse tank, then an acid bath to remove oxidation, a rinse tank, then a phosphatizing tank maintained at an elevated temperature. Phosphatizing is a lengthy process with strictly controlled parameters throughout the operation in order to achieve the desired surface.
Many of the small parts in internal combustion engines have been given iron-phosphate conversion surfaces such as cams, tappets, piston rings. Phosphatizing of these parts did not achieve universal acceptance in the automotive or other industries due to the added costs.
Organic phosphate compounds have also been widely used as additives in lubricating oils to impart EP (Extreme Pressure) properties to oils. It has been demonstrated that some of the organic phosphates had, over time, burnished into gears and other metal moving parts and have provided good metal protection. This burnishing in of phosphates to metals occurred in a spotty, inconsistent, and uncontrollable manner thus limiting the pursuit of this application in machinery and equipment.
In attempts to improve lubricating properties many additives have been added to motor oils to improve lubricity. A whole range of of compounds have been used, including PTFE (TEFLON.TM. of DuPont) molybdenum di-sulfide compounds, halogenated hydrocarbons, and colloidal suspensions of metal salts of lead, or copper or zinc. All of these additives either were ineffective or created problems within the engines that were supposed to benefit from the additives. The most widely used additive, PTFEs and their isomers, have been widely discredited in several scientific studies. Molybdenum di-sulfides presented problems with fouling of oil filters. Lead was a very effective additive; however, the toxicity of lead and severe environmental problems precluded lead's further use as an additive. Halogenated hydrocarbons present environmental problems and can create corrosion problems in engines.
Race car drivers spend thousands of dollars per engine to increase horsepower for better performance. The addition of 1 or 2 horsepower to an engine is, in many cases, the difference between a winning race and being an also ran. To accomplish any increase in horsepower engines are disassembled then may be chrome plated, or be ceramic lined, or have other type of metallic surfaces applied to moving parts to reduce friction. Such treatments are very expensive and can cost thousands of dollars for the engine treatment.
It has long been recognized that an inexpensive method of achieving an iron-phosphate conversion surface on all sliding, moving metal parts in engines, pumps, gearboxes, etc., would result in enhanced performance characteristics for the equipment. The enhanced performance would result from the reduction of friction, thereby reducing energy consumption, and enhancing the performance of lubricating oils. A process which would achieve an inexpensive iron/phosphate surface, specifically by achieving an iron/phosphate surface in the completed machinery engines, would be extremely valuable; for instance an internal combustion engine will have over 200 parts in cams, lifter, cylinders, timing chains. By applying a friction reducing surface to the parts internal combustion engines race car drivers enhance horsepower, fuel usage and better cooling of the engines.